A comparison of the valence electron configuration of the elements, Sm and Eu suggests that
(a)Sm is a better one electron reductant than Eu
(b)Sm is a better one electron oxidant than Eu
(c)Facile oxidation state is +2 for both the elements
(d)both of these display similar redox behaviour
Answer
Answer: A ✓ checked by 4AB · confidence medium
The source book printed B; on checking, A is correct — see the explanation.
Explanation
Eu²⁺ (f⁷) is far more stable than Sm²⁺ (f⁶): E°(Ln³⁺/Ln²⁺) = −0.35 V for Eu but −1.55 V for Sm. Hence Sm(II) is the much stronger one-electron reductant, and Eu(III) the better oxidant.